1. Field of the Invention
This hand tool generally relates to a class of adjustable locking pliers (such as the type utilizing a locking toggle), and more particularly to adjustable locking pliers embodying opposing jaw members having parallel relationship (being also categorized as toggle wrenches), with handles economically constructed incorporating an ergonomic design.
2. Background Art
Known to the art are conventional toggle locking pliers and automatic adjusting locking pliers having opposing jaw members communicating pivotally, with a movable jaw member applying clamping force by its levered rotation around a central point housed in the body of these types of locking pliers, and having a fixed upper handle located above a movable lower handle.
Also known to the art are parallel grip toggle locking pliers having opposing jaw members communicating pivotally in an adjustable parallel relationship, with a movable jaw member applying clamping force by its levered rotation around multiple points housed in the body of parallel grip toggle locking pliers, and having a fixed upper handle located above a movable lower handle.
Also known in the art are parallel action toggle locking wrenches having opposing jaw members communicating in an adjustably slidable parallel relationship, with a movable lower jaw member contacting and sliding along multiple planes (more than two) of parallel opposing outer side edge length dimensions of a rectangularly shaped support member, and having a movable upper handle located above a fixed lower handle.
Also known in the art are parallel action toggle locking wrenches having opposing jaw members communicating in an adjustably slidable parallel relationship, with a movable lower jaw member contacting and sliding along multiple planes (two or more) of parallel opposing side edge length dimensions housed in and constructed to a triangularly shaped support member, and having a movable upper handle located above a fixed triangular lower handle. As it is known in the prior art concerning the toggle wrenches mentioned above; all parallel action toggle locking wrenches have in common a movable lower jaw member constructed with parallel opposing flat surface structures contacting and sliding along parallel opposing flat surface structures of the support member—resulting in a tendency for the movable lower jaw member to bind (while opposing jaw members are under pressure) along the above-mentioned side edge length dimensions of the support member. This binding pressure makes releasing the movable lower jaw member from the side edge length dimensions of the support member difficult to impossible during the upper handle and jaw release of clamping pressure from the clamped object.
The disadvantages of conventional toggle locking pliers and automatic adjusting locking pliers are that the jaw members are not always in parallel relationship—resulting in jaw slippage from less surface area contact with a substantially square object (or objects) being clamped. Furthermore, conventional toggle locking pliers and automatic adjusting locking pliers have the jaw width adjustment (toggle angle adjustment) being difficult to determine and keep secure during the clamping procedure—resulting in an awkward over adjustment and subsequent readjustment of an adjustment screw or toggle stop screw before different size objects are to be clamped.
The disadvantages of the previously mentioned parallel grip toggle locking pliers are that the lower jaw members are not always in a ninety degree angle relationship with a rectangularly shaped support member—resulting in jaw slippage from less surface area contact with a substantially square object (or objects) being clamped. This is due to the fact the rectangularly shaped support member provides a third flat contact surface plane for which a substantially square object (or objects) can be additionally braced against. Furthermore, parallel grip toggle locking pliers have a fixed upper handle located above a movable lower handle, as opposed to handle construction having a movable upper handle located above a fixed lower handle. This type of fixed upper handle construction results in a lost of mechanical leverage gained by gravity, because the user of parallel grip toggle locking pliers has to rely on finger grip strength alone when squeezing the movable lower handle towards the fixed upper handle, rather than using body weight to help assist in pushing down on and squeezing a movable upper handle towards a fixed lower handle.
A further disadvantage of parallel action toggle locking wrenches and parallel grip toggle locking pliers is that handle construction is not of ergonomic design. This results in an uncomfortableness and awkwardness during handle operation by the reduction of hand grip.
A still further disadvantage of parallel action toggle locking wrenches is a fixed lower handle design having an externally mounted toggle adjustment assembly—resulting in an awkwardness during handle operation by the reduction of hand grip. This is because there is a greater possibility of the user grabbing onto the uncomfortable surface of the threaded section of the tool.
Another disadvantage of conventional toggle locking pliers, parallel action toggle locking pliers, and automatic adjusting locking pliers is cost of manufacture.
Still other disadvantages of automatic adjusting locking pliers are the awkward release of the locking mechanism, and the awkward position of the locking mechanism when in the unlocked mode, and jaw members being not parallel when clamped.